Spark plug



Oct. 3, 1939.

.W M. HART SPARK PLUG Filed Oct. 13, 1958 Patented Oct. 3, 1939 UNITEDSTATES PATENT OFFICE 1 Claim.

This invention relates to the class of ignition devices for explosiveengines and, pertains particularly to improvements in spark plugs.

Operators of internal combustion engines such as automobile engines areaware that adjustments frequently have to be made of the electrodes orsparking points of the spark plugs in order that the particular cylinder01' each spark plug may operate at maximum efliciency. Such adjustmentsare primarily required as a result 01' the burning away or pitting ofthe electrodes although it may be found that the initial setting for thepoints or electrodes of the plug is not correct for the particularcylinder in which the plug is used. When such a change in the setting01' the electrodes is necessary, the ordinary plug has to be removedfrom the cylinder and the points 01' the electrodes bent to bring theminto'proper spaced relation and then the plug must be put back and theengine operated to determine whether the setting is correct.

The present invention has for its primary object to provide an improvedspark plug whereby an adjustment of one electrode relative to the othermay be readily made without necessitating removing the plug from theengine cylinder, thus making it possible to keep the engine runningwhile adjusting the electrodes so that it can be readily determined bythe manner in which the engine is running just when the adjustment hasbeen correctly made in order to obtain maximum operating efliciency fromthe cylinder in which the particular plug under consideration islocated.

Another object of the invention is to provide an improved spark plugwherein the center electrode and porcelain carrying thesame may belongitudinally moved through the shell which is threaded into the enginecylinder head and which carries the grounded electrode, thus making itpossible to adjust the electrodes without'running the risk of receivinga shock as the part of the plug which must be touched for the purpose of{)noaking the adjustment is grounded to the engine The invention will bebest understood from a consideration oi. the following detaileddescription taken in connection with the accompanying drawing iormingpart of this specification, with the understanding, however, that theinvention is not to be confined to any strict conformity with theshowing of the drawing but may be changed or modified so long as suchchanges or modifications mark no material departure from the salientfeatures of the' invention as expressed in the appended claim.

In the drawing:

Fig. 1 is a view in side elevation of the spark plug embodying thepresent invention.

Fig. 2 is a longitudinal section throughthe same and through a portiononly of the center electrode 5 porcelain.

Fig. 3 is a Fig. 2.

Referring now more particularly to the draw ing, the numeral Idesignates a portion of an engine cylinder head in which is the usualthreaded opening 2 for the reception of the lower or base portion of aspark plug.

The spark plug of the present invention comprises a metallic base orshell body 3 having an enlarged upper end portion of polygonal contouras indicated at 4 to facilitate the attachment of a wrench or similartool thereto so that the reduced lower end portion 5 of the shell whichis screw threaded as indicated at 6, may be threaded into the opening 2of the cylinder head.

The usual passage I is formed through the shell and the upper end ofthis passage is of enlarged diameter as indicated at 8 and screwthreaded as indicated at 9.

The lower edge of the shell 3 has secured thereto the usual groundelectrode III which in the present structure has a terminal upwardlydirected portion II which is disposed approximately upon thelongitudinal center of the plug body.

Threadably secured in the portion 8 of the shell 3 is a sleeve l2, thelower end of the exterior being threaded as indicated at ii forengagement with the threads 9 and the upper end of the interior beingthreaded as indicated at It for engagement by the exteriorly threadedend of a packing collar IS. The lower interior portionof the sleeve I2is formed to provide a shoulder IS on which the usual packing ring I! isplaced and this ring and shoulder support the central electrodeporcelain body l8 which extends longitudinally through the sleeve l2 andthrough the major upper end portion of the shell 3 as illustrated. Thisporcelain body has the usual enlarged central part I9 which providesupper and lower shoulders, the lower one of which rests upon the packingring I! as illustrated, while the upper one has pressed thereagainst thepacking ring 20 by the collar l5 which surrounds the porcelain.

Through the center of the porcelain body the primary electrode 2|passes, the lower end of this electrode being in spaced relation withthe upwardly directed end of the grounded electrode It. The uppenend ofthe electrode 2| is formed in sectional view on the line 3-4 of in thethreaded aperture of the engine cylinder head and the looking or bindingnut 23 is loosened or backed away from the upper end of the shell sothat the sleeve, to which the central electrode carrying portion [8 isfirmly fixed, may be rotated and thus moved, and move the centerelectrode and porcelain, longitudinally. This longitudinal movement ofthe central electrode will, of course, change the distance between thelower end of the electrode and the grounded electrode 10 and when it hasbeen determined by the running action of the cylinder in which the plugis secured when the cylinder is operating at greatest efficiency, thebinding or lock nut 23 is then screwed down into tight engagement withthe upper end of the shell 3 while holding the sleeve l2 againstrotation. The sleeve, together with the porcelain and center electrode,will then be firmly fixed and if, after the electrode points have becomepitted or for any other reason further adjustment is necessary, the nut23 may be loosened and the described procedure repeated until thecylinder is again operating properly.

What is claimed is:

A spark plug of the character described, comprising an elongatedcylindrical base shell having one end exteriorly threaded for connectionin the spark plug opening of an engine cylinder, the other end of theshell being interiorly threaded, a sleeve having an exteriorly threadedportion for engagement in the interiorly threaded end of said shell,said sleeve being interiorly reduced at the said threaded end, anelongated body .of in sulation having a portion of maximum diametersubstantially midway of its ends and extending through said sleeve withthe said portion thereof disposed in the sleeve and supported thereinupon the part of reduced diameter, the portion of the insulation bodyextending through the sleeve portion of reduced diameter extendingthrough the major portion of the shell and terminating short of the endthereof which enters the engine cylinder opening, an electrode extendinglongitudinally through said body of insulation, a locking ringencircling and having threaded engagement with said sleeve and adaptedto bear against the top end of said shell to maintain the sleeve inadjusted position therein, and a clamping ring encircling said body ofinsulation and threadably engaging the interior of said sleeve to securethe insulation body therein, and a ground electrode integral with theshell and having spaced relation with the inner end of said firstelectrode.

WILLARD M HART.

